When machining is performed using a laser processing machine or a machine tool, tracing control is performed in which a position of a tip of worktool is controlled to move along a command path. The tracing control is executed by servo control such that an actual position of each movable axis of a machine tracks a position command value of corresponding movable axis.
In a typical machine, one motor is used for one direction of movement. In a case where servo control is performed using one motor for one direction of movement, tracking error caused by response delay of a servo control system becomes a problem. In addition, because there is a limitation in a thrust which can be generated by a motor, acceleration at which the motor can drive is limited, which results in a problem in that rapid response cannot be achieved. When a high-speed operation of at least several tens of meters per minute is required, an influence of tracking error or insufficient response is particularly remarkable.
Accordingly, a device has been proposed in which an additional motor with rapid response is added to a motor which has been used so far, and motion in one direction of movement is controlled by using two motors having different response. For example, Patent Literature 1 discloses a technique of performing tracing control using a cooperative control system which includes a low-speed servo system and a high-speed servo system having higher response than the low-speed servo system.